If you use Exchange Online Protection for your email hygiene, you know that you can notify your end-users when emails have been put in quarantine.
This is notification is sent using a generic Microsoft email address (firstname.lastname@example.org) and subject (Microsoft 365 security: You have messages in quarantine).
Well, go news as you can now customize these sender and subject.
To do so, connect to your Security portal (https://security.microsoft.com/) to access the Emails & collaboration\Policies & rules to access the Threat policies option
Once there access the Quarantine policies to edit the Global Settings
There you can customize the display name and email address of the sender as well the subject
NOTE if you also have configured the multi language, you can define custom details for each of the language. The proposed display name is matching the corresponding language